Power converter, and photovoltaic element module and power generator using the same

ABSTRACT

To improve the conversion efficiency of a power converter in a solar cell module in which a solar cell module main body containing a solar cell is integrated with a power converter for converting the output power from the solar cell module main body, a material having small thermal conductivity is used as a member ( 205 ) of a protective case for protecting the power converter to be fixed to the solar cell module main body containing the solar cell, thereby preventing easy conduction of heat from the solar cell module main body heated to high temperatures to a power conversion circuit ( 201 ). A material having large thermal conductivity is used as a member ( 206 ) of a protective case for fixing the power conversion circuit ( 201 ), thereby allowing easy radiation of heat generated in the power conversion circuit ( 201 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a solar cell module having asolar cell and a power converter, and a power generator using this solarcell module.

BACKGROUND OF THE INVENTION

[0002] Recently, a large number of solar power generating systems areinstalled to solve environmental problems and the like. In thesesystems, electric power generated by a solar cell (to be also referredto as a “photovoltaic element” hereinafter) is converted by a powerconverter, and this power is supplied to a load in a house and/or acommercial power system (to be referred to as a “system” hereinafter).

[0003] In addition, a solar cell module (photovoltaic element module)has attracted attention as a small- or medium-scale solar powergenerating system or as an emergency power supply. In this solar cellmodule, a small power converter (to be referred to as a “powerconverter” hereinafter), called an Module Integrated Converter (MIC),for converting electric power generated by a solar cell (photovoltaicelement) is attached to the surface (to be referred to as a “rearsurface” hereinafter) opposite to the solar cell light-receiving surface(to be referred to as a “light-receiving surface” hereinafter).

[0004] Unfortunately, this solar cell module has the following problem.That is, the temperature of the light-receiving surface of the solarcell module rises, and the heat is conducted to the rear surface of thesolar cell module. This heat conduction raises not only the temperatureof the rear surface on which the power converter is usually mounted, butalso the temperature of a power conversion-circuit installed in thispower converter.

[0005] That is, when the heat conduction from the light-receivingsurface of the solar cell module raises the temperature of the powerconverter, the performance lowers and the power conversion efficiencyworsens. In some cases, the power converter may be damaged.

[0006] As described above, if insulation of the heat conducted from thesolar cell module (photovoltaic element module) to the power converterand radiation of the heat from the power converter are insufficient, thepower conversion efficiency worsens, and the power converter may bedamaged, or the life of the power converter may shorten even if noimmediate damage occurs. To solve this heat problem, Japanese PatentLaid-Open No. 9-271179 discloses an arrangement in which a powerconverter is mounted in a gap formed in the rear surface of a solar cellmodule.

[0007] When, however, this solar cell module is to be integrated with abuilding material such as a roofing material, this rear-surface space isvery narrow, so the power converter must also be very small.Accordingly, when the power converter is mounted in a gap as in theabove disclosure, a large space is necessary, and this interferes withdownsizing of the solar cell module. Also, the strength of a structurehaving a gap as in the above disclosure is low from a viewpoint ofmechanics.

SUMMARY OF THE INVENTION

[0008] The present invention has been made to solve the problems of theprior art described above, and has as its object to provide a solar cellmodule (photovoltaic element module) in which a solar cell module(photovoltaic element module) main body containing a solar cell(photovoltaic element) is integrated with a power converter forconverting output electric power from the solar cell, and which issuited to downsizing and capable of improving the efficiency andreliability of the power converter.

[0009] To achieve the above object, a solar cell module of an embodimentaccording to the present invention has the following arrangement. Thatis, a power converter comprises a power conversion circuit forconverting an output from a photovoltaic element and outputting theconverted output, and a protective case containing the power conversioncircuit, characterized in that the protective case comprises a firstportion for fixing the protective case to a predetermined portion of aphotovoltaic element module having the photovoltaic element, and asecond portion for fixing the power conversion circuit, and the firstand second portions are made of materials different in thermalconductivity.

[0010] For example, the power converter is characterized in that thethermal conductivity of the material of the first portion is smallerthan that of the material of the second portion.

[0011] For example, the power converter is characterized in that thematerial of the first portion is a plastic material containing onemember selected from the group consisting of polycarbonate, polyamide,polyacetal, modified PPO (PPE), polyester, polyallylate, unsaturatedpolyester, a phenolic resin, an epoxy resin, polybutyleneterephthalate,nylon, polypropyrene, polyvinyl chloride, and an ABS resin.

[0012] For example, the power converter is characterized in that thematerial of the second portion contains one member selected from thegroup consisting of an aluminum plate, stainless steel plate,zinc-plated steel plate, galvalume steel plate, titanium steel plate,and stainless steel plate.

[0013] For example, the power converter is characterized in that thematerial of the second portion is a resin mixed with a thermallyconductive material.

[0014] For example, the power converter is characterized in that thethermally conductive material contains at least one of a metal powder,metal oxide, metal fibers, metal-coated glass beads, and syntheticfibers.

[0015] For example, the power converter is characterized in that a metalforming the thermally conductive material contains at least one of Al,Cu, Ni, ZnO, SnO₂, Ag, and stainless steel.

[0016] For example, the power converter is characterized in that thethermally conductive material contains at least one of carbon black,carbon fibers, and graphite.

[0017] For example, the power converter is characterized in that thematerial of the first portion is a plastic material containing onemember selected from the group consisting of polycarbonate, polyamide,polyacetal, modified PPO (PPE), polyester, polyallylate, unsaturatedpolyester, a phenolic resin, an epoxy resin, polybutyleneterephthalate,nylon, polypropyrene, polyvinyl chloride, and an ABS resin.

[0018] For example, the power converter is characterized in that thepower conversion circuit is fixed in contact with a surface of thesecond portion.

[0019] For example, the power converter is characterized in that thepower conversion circuit is fixed away from the second portion.

[0020] For example, the power converter is characterized in that thepower conversion circuit is fixed to the second portion by using fixingmeans.

[0021] For example, the power converter is characterized in that thefixing means is mechanical fixation using a screw or fixation using anadhesive or filler.

[0022] For example, the power converter is characterized in that anadhesive or filler is packed between the protective case and the powerconversion circuit.

[0023] For example, the power converter is characterized in that thepower converter is an inverter which converts DC power into AC power.

[0024] For example, the power converter is characterized in that thepower conversion circuit is mounted on a substrate having a metal core.

[0025] For example, the power converter is characterized in that thepower converter is a DC/DC converter which converts DC power intoanother DC power having a different voltage.

[0026] For example, the power converter is characterized in that thephotovoltaic element contains one member selected from the groupconsisting of a silicon semiconductor, compound semiconductor,single-crystal silicon, polysilicon, amorphous silicon, and thin-filmpolysilicon.

[0027] For example, the power converter is characterized in that thephotovoltaic element is filled with a transparent insulating member andcontained in a main body of the photovoltaic element module.

[0028] For example, the power converter is characterized in that theinsulating member is rendered transparent by the use of one memberselected from the group consisting of an ethylene-vinyl acetatecopolymer (EVA), ethylene-methyl acrylate copolymer (EMA),ethylene-ethyl acrylate copolymer (EEA), and polyvinyl butyral resin.

[0029] To achieve the above object, a photovoltaic element module of anembodiment according to the present invention has the followingarrangement. That is, a photovoltaic element module comprises a powerconverter comprising a power conversion circuit for converting an outputfrom a photovoltaic element and outputting the converted output, and aprotective case containing the power conversion circuit, and aphotovoltaic element module main body having the photovoltaic element,characterized in that the protective case comprises a first portion forfixing the protective case to a predetermined portion of thephotovoltaic element module having the photovoltaic element, and asecond portion for fixing the power conversion circuit, and the firstand second portions are made of materials different in thermalconductivity.

[0030] To achieve the above object, a power generator of an embodimentaccording to the present invention has the following arrangement. Thatis, a power generator uses a photovoltaic element module comprising apower converter comprising a power conversion circuit for converting anoutput from a photovoltaic element and outputting the converted output,and a protective case containing the power conversion circuit, and aphotovoltaic element module main body having the photovoltaic element,characterized in that the protective case comprises a first portion forfixing the protective case to a predetermined portion of thephotovoltaic element module having the photovoltaic element, and asecond portion for fixing the power conversion circuit, and the firstand second portions are made of materials different in thermalconductivity.

[0031] For example, the power generator is characterized in that thepower generator comprises a plurality of photovoltaic element modulemain bodies, and the plurality of photovoltaic element module mainbodies are connected to the power converter.

[0032] Other features and advantages of the present invention will beapparent from the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

[0034]FIG. 1 is a sectional view showing the arrangement of a solar cellmodule of the first embodiment according to the present invention;

[0035]FIG. 2 is a sectional view showing the arrangement of a powerconverter of the first embodiment according to the present invention;

[0036]FIG. 3 is a sectional view for explaining a method of mounting thepower converter of the first embodiment;

[0037]FIG. 4 is a sectional view showing the arrangement of a powerconverter of the second embodiment according to the present invention;

[0038]FIG. 5 is a sectional view showing the arrangement of a powerconverter of the third embodiment according to the present invention;

[0039]FIG. 6 is a sectional view showing the arrangement of a powerconverter of the fourth embodiment according to the present invention;

[0040]FIG. 7 is a sectional view showing the arrangement of a powerconversion circuit of the fourth embodiment according to the presentinvention;

[0041]FIG. 8 is a sectional view showing the arrangement of a solar cellmodule of the fifth embodiment according to the present invention; and

[0042]FIG. 9 is a sectional view showing the arrangement of a solar cellmodule of the sixth embodiment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Preferred embodiments of the present invention will now bedescribed in detail in accordance with the accompanying drawings.

[0044] An embodiment according to the present invention will beexplained below with reference to the accompanying drawings.

[0045] Although the explanation will be made by using a solar cellmodule according to the present invention, the scope of the invention isno limited to the described examples.

[0046] [First Embodiment]

[0047] An outline of a solar cell module 101 will be described first,and then each constituent element will be explained. Finally, a methodof manufacturing a solar cell module main body 110 and a power converter107 and a method of mounting the power converter 107 onto the solar cellmodule main body 110 will be explained.

[0048]FIG. 1 is a schematic sectional view showing the arrangement ofthe solar cell module 101 of the first embodiment according to thepresent invention.

[0049] That is, FIG. 1 shows an example of the solar cell module 101obtained by integrating the solar cell module main body 110 containing aphotovoltaic element (solar cell) 106 and the power converter 107.

[0050] The solar cell module main body 110 is made up of aweather-resistant film 102, a filler 104, the photovoltaic element 106,a filler 105, and a rear-surface reinforcing material 103. Output leadwires 108 for extracting output are connected to the power converter107.

[0051] The weather-resistant film 102 is formed on a light-receivingsurface 109 of the solar cell module main body 110. The photovoltaicelement 106 is placed inside the light-receiving surface 109. Thelight-transmitting fillers 104 and 105 are formed around thephotovoltaic element 106 to fix this photovoltaic element 106.

[0052] The rear-surface reinforcing material 103 for reinforcement isformed on a rear surface 111 opposite to the light-receiving surface 109of the solar cell module 101. On this rear-surface reinforcing material103, the power converter 107 for converting electric power generated bythe photovoltaic element 106 is placed.

[0053] A weather-resistant transparent film is used as theweather-resistant film 102 as a protective material of thelight-receiving surface 109. A metal steel plate such as used as a metalroof is used as the rear-surface reinforcing material 103. The surfaceof this metal steel plate can also be coated with a polyester resin orfluorine resin in order to increase, e.g., the weather resistance.

[0054] The characteristic feature of the solar cell module 101 havingthe above structure is that this solar cell module 101 can be easilyformed, by bending or the like, into the shape of a roofing materialsuch as a folded plate shape, roll shape, or stepping roof shape, orinto the shape of a building material such as a wall material.

[0055] In particular, an amorphous silicon solar cell using a conductivesubstrate to be described later has high mechanical strength andflexibility. Therefore, the solar cell module 101 using this amorphoussilicon solar cell has a high degree of freedom of shape and hence canbe formed into various roof shapes and wall shapes.

[0056] [Photovoltaic Element]

[0057] The photovoltaic element 106 is not particularly limited, and itis possible to use, e.g., a single-crystal silicon solar cell,polysilicon solar cell, and amorphous silicon solar cell each consistingof a silicon semiconductor.

[0058] Compound semiconductors can also be used. Examples are a groupIII-V compound solar cell, group II-VI compound solar cell, and groupI-III-VI compound solar cell.

[0059] In particular, an amorphous silicon solar cell restores its powergeneration efficiency by an annealing effect at a high temperature, andcan be formed on a film or on a conductive-material substrate by usingthe thin film technologies. This can reduce the weight of thephotovoltaic element 106 itself.

[0060] Accordingly, when the solar cell module 101 integrated with abuilding material is to be formed, it is particularly preferable to usean amorphous silicon solar cell as the photovoltaic element 106.

[0061] [Power Converter]

[0062] As the power converter 107, it is possible to use an inverterwhich converts DC power into AC power, or a DC/DC converter whichconverts DC power into another DC power having a different voltage(i.e., which raises or lowers the voltage).

[0063] In the following description, a case in which this powerconverter 107 is an inverter will be explained as an example withreference to FIG. 2.

[0064]FIG. 2 is a sectional view of the power converter 107.

[0065] This power converter 107 comprises input lead wires 204 connectedto the photovoltaic element 106, a power conversion circuit 201 forpower conversion, and the output lead wires 108 for power output. Thepower converter 107 further includes a waterproof bushing 203 and firstand second members 205 and 206 as sheathing materials for protecting theabove components.

[0066] The waterproof bushing 203 prevents the invasion of rainwaterfrom the output lead wires 108 into the power converter 107. The firstmember 205 is a portion to be attached to the rear-surface reinforcingmaterial 103 of the solar cell module main body 110. This first member205 is made of a resin having a high heat resistance, since the firstmember 205 is brought into contact with the rear-surface reinforcingmaterial 103 which is heated to high temperatures. The second member 206is made of a metal superior in heat radiation properties.

[0067] The power conversion circuit 201 includes a booster circuit 201a, an inverter circuit 201 b, a control circuit 201 c, a systeminterconnection protection circuit (not shown), and a communicationcircuit (not shown). The booster circuit 201 a boosts an output DCvoltage from the photovoltaic element 106 into an input voltage to theinverter circuit. The inverter circuit 201 b converts DC power into ACpower. The control circuit 201 c controls activation/stop of powerconversion, optimization of the operating point of the photovoltaicelement 206, and the operation mode.

[0068] As the booster circuit 201 a, a step-up chopper circuit, variouskind of publicly known circuits can be used. As the inverter circuit 201b, a voltage-fed inverter using an IGBT or MOSFET as a switching elementis preferred. By driving the gate of this switching element by a controlsignal from the control circuit 201 c, AC power having a desiredfrequency, phase, and voltage can be obtained.

[0069] The control circuit 201 c includes, e.g., a CPU, PWM waveformcontrol circuit, frequency voltage reference generator, currentreference generator, mode switch, and switching control circuit. Thiscontrol circuit 201 c can also be externally operated via communicationlines or the like. Furthermore, a plurality of power converters 107 canbe simultaneously controlled by placing the control circuit 201 coutside these power converters 107.

[0070] The first member 205 as a sheathing material of the powerconverter 107 is brought into contact with the rear-surface reinforcingmaterial 103 of the solar cell module main body 110. In order that heatof the rear-surface reinforcing material 103 heated to a hightemperature be not readily conducted to the power conversion circuit 201inside the power converter 107 or to the second member 206, this firstmember 205 must be made of a material having small thermal conductivity.It is particularly favorable to use heat-resistant plastic materialssuch as polycarbonate, polyamide, polyacetal, modified PPO (PPE),polyester, polyallylate, unsaturated polyester, phenolic resin, epoxyresin, polybutyleneterephthalate, nylon, polypropyrene, polyvinylchloride, and ABS (Acrylonitrile.Butadiene.Styrene) resin.

[0071] To efficiently radiate heat from the booster circuit 201 a, theswitching element of the inverter circuit 201 b, and autility-interactive reactor, the second member 206 is preferably made ofa high-thermal-conductivity material having high mechanical strength andexcellent heat radiation properties. For example, a metal whichfacilitates mounting of the power converter 107 is favored. Aluminum,copper, and their alloys are particularly favored.

[0072] The power conversion circuit 201 is mounted on a printed circuitboard or some other substrate 209 superior in heat radiation properties.This substrate 209 is fastened to the second member 206 by using screws207.

[0073] Heat generated by the power conversion circuit 201, therefore, isconducted to the second member 206 via the substrate 209 having superiorheat radiation properties, and radiated from this second member 206.

[0074] The substrate 209 can also be fastened by using, e.g., anadhesive or filler, instead of the screws 207.

[0075] Additionally, a heat-conducting member can be further interposedbetween the power conversion circuit 201 and the second member 206 topromote the radiation of heat from this second member 206.

[0076] [Rear-surface Reinforcing Material]

[0077] The material of the rear-surface reinforcing material 103 of thesolar cell module main body 110 is not particularly restricted. However,a material which has high mechanical strength and which is strained orwarped little upon temperature changes is preferred. For example,reinforced glass and a metal plate can be used.

[0078] Examples of usable materials are metals, carbon fibers, FRP(Fiber Reinforced Plastics), ceramics, polycarbonate, glass, andTedlar/Al/Tedlar.

[0079] For example, it is possible to use an aluminum plate, stainlesssteel plate, titanium plate, and plated steel plates such as azinc-plated steel plate and galvalume steel plate. However, the materialis not limited to these metal plates.

[0080] Also, the durability of any of the above materials can beincreased by performing anodic oxidation on the surface or by coatingthe surface with a resin such as a polyester resin or acrylic resin.

[0081] The solar cell module 101 integrated with a metal roofingmaterial is sometimes bent when in use. However, when a metal plate isused as the rear-surface reinforcing material 103, this solar cellmodule 101 can be handled in the same manner as general metal roofingmaterials.

[0082] [Manufacturing Methods]

[0083] [Manufacture of Solar Cell Module]

[0084] An example of a method of manufacturing the solar cell modulemain body 110 will be explained below.

[0085] As the materials, ETFE (EthyleneTetraFluoroEthylene) is used asthe weather-resistant film 102, a 0.4-mm thick steel plate coated with apolyester resin is used as the rear-surface reinforcing material 103,and EVA (Ethylene-Vinyl Acetate copolymer, weather-resistant grade) isused as the fillers 104 and 105.

[0086] As shown in FIG. 1, the rear-surface reinforcing material 103 isset, and the filler 105, the photovoltaic element 106, the filler 104,and the weather-resistant film 102 are laminated in this order on therear-surface reinforcing material 103, thereby obtaining a laminatedbody.

[0087] A vacuum laminator is then used to melt the fillers 104 and 105of this laminated body at 150° C. Consequently, it is possible tomanufacture the solar cell module main body 110 in which thephotovoltaic element 106 is resin-encapsulated between the rear-surfacereinforcing material 103 and the weather-resistant film 102.

[0088] [Manufacture of Power Converter]

[0089] An example of a method of manufacturing the power converter 107will be described below with reference to FIG. 2.

[0090] First, the waterproof bushing 203 is attached to the secondmember 206.

[0091] The power conversion circuit 201 is mounted on the substrate 209beforehand.

[0092] The output portion of this power conversion circuit 201 iselectrically connected to the output lead wires 108 by soldering orscrewing.

[0093] The input lead wires 204 are electrically connected to the inputportion of the power conversion circuit 201 by soldering.

[0094] After the output lead wires 204 are inserted into the waterproofbushing 203, the power conversion circuit 201 is held in a predeterminedposition and fastened to the second member 205 by the screws 207.

[0095] Finally, the power converter 107 can be completed by attachingthe first member 205 to the opening of the second member 206 by anadhesive (not shown).

[0096] [Mounting of Power Converter]

[0097] A method of mounting the power converter 107 onto the solar cellmodule main body 110 will be described below with reference to FIG. 3.

[0098] The rear-surface reinforcing material 103 is a rectangular steelplate coated with a polyester resin. A hole about 15 mm in diameter isformed beforehand in that portion of this rear-surface reinforcingmaterial 103, which corresponds to an electrode (not shown) forextracting power from the photovoltaic element 106. However, this holeis filled with the filler 105 when the solar cell module main body 110is manufactured.

[0099] First, therefore, the filler 105 in this terminal portion isremoved, and then the input lead wires of the power converter 107 aresoldered to the electrode (not shown) of the photovoltaic element 106.

[0100] Subsequently, a predetermined amount of a silicone adhesive 301is applied to the first member 205 of the power converter 107, and thepower converter 107 is adhered to the rear-surface reinforcing material103.

[0101] In this manner, the solar cell module 101 in which the powerconverter 107 is integrated with the solar cell module main body 110 ismanufactured.

[0102] If the power converter 107 is an inverter explained previously, aplurality of such solar cell modules 101 connected to each other can beused in a house load or/and interconnected to the utility line.

[0103] When a predetermined solar radiation amount is given to the solarcell module 101 thus manufactured, the power converter 107 converts DCpower generated by the photovoltaic element 106 into AC power, and thisAC power can be output through the output lead wires 108.

[0104] The first member 205 having small thermal conductivity preventsthe conduction of heat from the solar cell module main body 110 heatedto a high temperature by solar radiation, to the power converter 107 viathe rear-surface reinforcing material 103.

[0105] Also, heat generated by the power converter 107 is effectivelyradiated from the second member 206 having large thermal conductivityvia the substrate 209. This can improve the conversion efficiency andreliability of the power converter 107.

[0106] [Second Embodiment]

[0107] A solar cell module 2101 of the second embodiment according tothe present invention will be described below.

[0108] A solar cell module main body 110 of this solar cell module 2101is exactly the same as the solar cell module main body 110 of the solarcell module 101 explained in the first embodiment, and only a powerconverter 2107 is different.

[0109] In the following explanation, therefore, that view showing thewhole configuration of the solar cell module 2101, which corresponds toFIG. 1, and a common description thereof will be omitted to avoidduplication, and only differences from the power converter 107 will beexplained by using the power converter 2107 shown in FIG. 4.

[0110] In this explanation of FIG. 4, the same reference numerals as inthe power converter 107 shown in FIG. 2 denote the same parts and adetailed description thereof will be omitted to avoid duplication, andonly differences will be explained.

[0111] [Power Converter]

[0112] First, the characteristic feature of the power converter 2107 ofthe second embodiment will be described below.

[0113] This power converter 2107 is characterized in that the radiationof heat generated from a power conversion circuit 201 inside the powerconverter 2107 is superior to that of the power converter 107 in thefirst embodiment.

[0114] The arrangement of the power converter 2107 will be explainednext.

[0115] The components of this power converter 2107 are the same as inthe power converter 107 except for the mounting positions; thesecomponents are mounted upside down.

[0116] That is, in this power converter 2107, the power conversioncircuit 201 is mounted on a printed wiring board having superior heatradiation properties. This printed wiring board is set using an adhesive2402 (or a filler) so as to come in contact with a second member 206.

[0117] The adhesive 2402 (or the filler) is interposed between the powerconversion circuit 201 and the second member 206 to fix the powerconversion circuit 201 to the second member 206. This adhesive 2402 alsoefficiently conducts heat generated by the power conversion circuit 201to the second member 206.

[0118] The adhesive 2402 (or the filler) is preferably one whichimproves workability when the power conversion circuit 201 is mounted.For example, an adhesive which has a short curing time and a viscosityof 40 to 1,000 Pa·s, i.e., which is not excessively viscous ispreferred. Examples are metals and metal oxides such as silver,aluminum, and aluminum oxide, and resins such as silicone, acryl, epoxy,and urethane each containing thermally conductive additives.

[0119] When a predetermined solar radiation amount is given to the solarcell module 2101 (not shown) in which the power converter 2107 shown inFIG. 4 is integrated with the solar cell module main body 110, the powerconverter 2107 converts DC power generated by a photovoltaic element 106into AC power, and this AC power can be output through output lead wires108.

[0120] A first member 205 having small thermal conductivity prevents theconduction of heat from the solar cell module 2101 heated to a hightemperature by solar radiation, to the power converter 2107 via arear-surface reinforcing material 103.

[0121] Also, heat generated by the power conversion circuit 201 iseffectively radiated from the second member 206 having large thermalconductivity via a substrate 209. This can improve the conversionefficiency and reliability of the power converter 2107.

[0122] [Third Embodiment]

[0123] A solar cell module 3101 of the third embodiment according to thepresent invention will be described below.

[0124] A solar cell module main body 110 of this solar cell module 3101is exactly the same as the solar cell module main body 110 of the solarcell module 101 explained in the first embodiment, and only a powerconverter 3107 is different.

[0125] In the following explanation, therefore, that view showing thewhole configuration of the solar cell module 3101, which corresponds toFIG. 1, and a common description thereof will be omitted to avoidduplication, and only differences from the power converter 107 will beexplained by using the power converter 3107 shown in FIG. 5.

[0126] In this explanation of FIG. 5, the same reference numerals as inthe power converter 107 shown in FIG. 2 denote the same parts and adetailed description thereof will be omitted to avoid duplication, andonly differences will be explained.

[0127] [Power Converter]

[0128] First, the characteristic feature of the power converter 3107 ofthe third embodiment will be described below.

[0129] This power converter 3107 is characterized in that the radiationof heat generated from a power conversion circuit 201 inside the powerconverter 3107 is superior to that of the power converter 107 in thefirst embodiment.

[0130] The arrangement of the power converter 3107 will be explainednext.

[0131] The components of this power converter 3107 are the same as inthe power converter 107 except for the mounting positions; thesecomponents are mounted upside down.

[0132] That is, in this power converter 3107, a printed wiring boardsuperior in heat radiation properties on which the power conversioncircuit 201 is mounted is set using an adhesive 3402 (and a filler) soas to come in contact with a second member 206.

[0133] The adhesive 3402 (and the filler) is packed in the entire powerconversion circuit 201 to fix the power conversion circuit 201 to thesecond member 206. This adhesive 3402 also efficiently conducts heatgenerated by the power conversion circuit 201 to the second member 206.

[0134] The adhesive 3402 (and the filler) can be any material providedthat the material has self-bonding properties, thermal contact bondingproperties, and adhesive properties, and can fix the power converter3107. Also, the adhesive 3402 (and the filler) can take the form of anyof a gel, paste, grease, sheet, and oil compound. However, the form isnot limited to these forms.

[0135] The adhesive 3402 (and the filler) is preferably one whichimproves workability when the power conversion circuit 201 is mounted.For example, an adhesive which has a short curing time and a viscosityof 40 to 1,000 Pa·s, i.e., which is not excessively viscous ispreferred. Examples are metals and metal oxides such as silver,aluminum, and aluminum oxide, and resins such as silicone, acryl, epoxy,and urethane each containing thermally conductive additives.

[0136] When a predetermined solar radiation amount is given to the solarcell module 3101 (not shown) in which the power converter 3107 shown inFIG. 5 is integrated with the solar cell module main body 110, the powerconverter 3107 converts DC power generated by a photovoltaic element 106into AC power, and this AC power can be output through output lead wires108.

[0137] A first member 205 having small thermal conductivity prevents theconduction of heat from the solar cell module 3101 heated to a hightemperature by solar radiation, to the power converter 3107 via arear-surface reinforcing material 103.

[0138] Also, heat generated by the power conversion circuit 201 iseffectively radiated from the second member 206 having large thermalconductivity via a substrate 209. This can improve the conversionefficiency and reliability of the power converter 3107.

[0139] [Fourth Embodiment]

[0140] A solar cell module 4101 of the fourth embodiment according tothe present invention will be described below.

[0141] A solar cell module main body 110 of this solar cell module 4101is exactly the same as the solar cell module main body 110 of the solarcell module 101 explained in the first embodiment, and only a powerconverter 4107 is different.

[0142] In the following explanation, therefore, that view showing thewhole configuration of the solar cell module 4101, which corresponds toFIG. 1, and a common description thereof will be omitted to avoidduplication, and only differences from the power converter 107 will beexplained by using the power converter 4107 shown in FIG. 6.

[0143] In this explanation of FIG. 6, the same reference numerals as inthe power converter 107 shown in FIG. 2 denote the same parts and adetailed description thereof will be omitted to avoid duplication, andonly differences will be explained.

[0144] [Power Converter]

[0145] First, the characteristic feature of the power converter 4107 ofthe fourth embodiment will be described below.

[0146] This power converter 4107 is characterized in that the radiationof heat generated from a power conversion circuit 201 inside the powerconverter 4107 is superior to that of the power converter 107 in thefirst embodiment.

[0147] That is, as will be described later, a substrate 209 on which thepower conversion circuit 201 is mounted has a metal core 703 in layersof this substrate 209. In addition, this metal core 703 projects to theoutside from end portions of a surface insulating layer 704. Theseprojecting portions form a mounting members 4602 to be fixed to a secondmember 206. Accordingly, the substrate 209 is mounted on the secondmember 206 by these mounting members 4602, so heat generated by thepower conversion circuit 201 can be effectively radiated to the outsidevia the second member 206.

[0148] The arrangement of the power converter 4107 will be explainednext.

[0149] The components of this power converter 4107 are the same as inthe power converter 107 except for the mounting positions; thesecomponents are mounted upside down.

[0150] That is, in this power converter 4107, the printed wiring boardor some other substrate 209 superior in heat radiation properties onwhich the power conversion circuit 201 is mounted is set using anadhesive or screws (not shown) so as to come in contact with the secondmember 206.

[0151]FIG. 7 is a detailed view of the power conversion circuit 4701.

[0152] This power conversion circuit 4701 is mounted on the printedcircuit board 209, and the metal core 703 is present in layers of thisprinted circuit board 209. The metal core 703 projects to the outsidefrom end portions of the surface insulating layer 704. These projectingportions 705 form the mounting members 4602 to be attached to the secondmember 206.

[0153] When a predetermined solar radiation amount is given to the solarcell module 4101 (not shown) in which the power converter 4107 shown inFIGS. 6 and 7 is integrated with the solar cell module main body 110,the power converter 4107 converts DC power generated by a photovoltaicelement 106 into AC power, and this AC power can be output throughoutput lead wires 108.

[0154] A first member 205 having small thermal conductivity prevents theconduction of heat from the solar cell module 4101 heated to a hightemperature by solar radiation, to the power converter 4107 via arear-surface reinforcing material 103.

[0155] Also, heat generated by the power conversion circuit 201 iseffectively radiated from the second member 206 having large thermalconductivity via the substrate 209. This can improve the conversionefficiency and reliability of the power converter 4107.

[0156] [Fifth Embodiment]

[0157] A power generator 5112 having a solar cell array 5111 whichincludes a plurality of solar cell module main bodies 5110 of the fifthembodiment according to the present invention, and a power converter5107, will be described below.

[0158] The solar cell array 5111 has an arrangement in which a pluralityof solar cell module main bodies 110 of the solar cell module 101explained in the first embodiment shown in FIG. 1 are connected. Thepower converter 5107 used in the power generator 5112 can be any of thepower converters 107, 2107, 3107, and 4107 explained in the first tofourth embodiments. However, input lead wires are preferably extractedfrom the same surface as output lead wires, or from a surface oppositeto the output lead wires.

[0159] In the following explanation, therefore, a description of commonportions explained in the first to fourth embodiments will be omitted toavoid duplication, and only differences will be described.

[0160] First, the characteristic feature of the solar cell module 5110of the fifth embodiment will be explained below.

[0161] As shown in FIG. 8, in the power generator 5112, the solar cellarray 5111 is formed by connecting a plurality of solar cell module mainbodies 5110 on a frame 5113. Accordingly, the power generator 5112 ofthe fifth embodiment can extract a large amount of electric power.

[0162] DC power collected to the solar cell array 5111 is input to andconverted by the power converter 5107. If necessary, the solar cellarray can be connected to the utility line.

[0163] If the power converter 5107 is an inverter which converts DCpower into AC power, the solar cell array 5111 is constructed byinterconnecting a plurality of solar cell module main bodies 5110 bylead wires extracted from the solar cell module main bodies 5110. Inthis case, the solar cell array 5111 can also be constructed byconnecting a plurality of solar cell module main bodies 5110 in series,and connecting the two ends of the series circuit to the power converter5107.

[0164] The solar cell array 5111 can be similarly constructed even whenthe power converter 5107 is a DC/DC converter. In this case, the solarcell array 5111 can be connected to the utility line by collecting powerfrom a plurality of main bodies 5110, converting the collected powerinto a desired DC voltage, and, where necessary, converting the DC powerinto AC power by a DC/AC converter such as a utility interactiveinverter.

[0165] Note that the solar cell module main body 5110 has a terminal box(not shown) for extracting power, or has a power extracting cable havinga waterproof connector at its end portion. The solar cell array 5111 isconstructed by interconnecting a plurality of solar cell module mainbodies 5110 by connecting the terminal boxes by lead wires or byconnecting the waterproof connectors.

[0166] When a predetermined solar radiation amount is given to the powergenerator 5112 thus manufactured, the power converter 5107 converts DCpower generated by the solar cell module main bodies 5110, and this ACpower can be output to the utility line.

[0167] A first member 205 having small thermal conductivity prevents theconduction of heat from the frame 5113 to a power conversion circuit201. Also, heat generated by the power conversion circuit 201 iseffectively radiated from a second member 206 having large thermalconductivity. This can improve the conversion efficiency and reliabilityof the power converter 5107.

[0168] [Sixth Embodiment]

[0169] A solar cell module 6101 of the sixth embodiment according to thepresent invention will be described below.

[0170] A solar cell module main body of this solar cell module 6101 isexactly the same as the solar cell module main body 110 of the solarcell module 101 explained in the first embodiment, and only a powerconverter 6107 is different.

[0171] In the following explanation, therefore, that view showing thewhole configuration of the solar cell module 6101, which corresponds toFIG. 1, and a common description thereof will be omitted to avoidduplication, and only differences from the power converter 107 will beexplained by using the power converter 6107 shown in FIG. 9.

[0172] In this explanation of FIG. 9, the same reference numerals as inthe power converter 107 shown in FIG. 2 denote the same parts and adetailed description thereof will be omitted to avoid duplication, andonly differences will be explained.

[0173] [Power Converter]

[0174] First, the characteristic feature of the power converter 6107 ofthe sixth embodiment will be described below.

[0175] This power converter 6107 is characterized in that the thermalconductivity of a second member 6206 is higher than that in the powerconverter 107 of the first embodiment.

[0176] The arrangement of the power converter 6107 will be explained.

[0177] The components of this power converter 6107 are the same as thepower converter 107 except for the second member. In the power converter6107, a substrate 209 on which a power conversion circuit 201 is mountedis fixed to the second member 6206 superior in heat radiationproperties.

[0178] More specifically, a modified PPO resin containing a copperpowder is used as the second member. Note that the material of thesecond member 6206 need only be a resin mixed with a thermallyconductive material. Examples of this thermally conductive material arefine metal powders, metal oxides, metal fibers, and metal-coated glassbeads using Al, Cu, Ni, ZnO, SnO₂, Ag, and stainless steel, andsynthetic fibers. Carbon black, carbon fibers, or graphite can also beused as the thermally conductive material. As the resin to be mixed withthe thermally conductive material, the various resins used in the firstmember 205 described in the first embodiment can be used.

[0179] Conduction of heat can be further improved by interposing ahigh-thermal-conductivity filler between the substrate 209 and thesecond member 6206 as in the third embodiment.

[0180] When a predetermined solar radiation amount is given to the solarcell module in which the power converter 6107 shown in FIG. 9 isintegrated with the solar cell module main body, the power converterconverts DC power generated by a photovoltaic element into AC power, andthis AC power can be output through output lead wires. A first member205 having small thermal conductivity prevents the conduction of heatfrom the solar cell module heated to a high temperature by solarradiation, to the power converter 6107 via a rear-surface reinforcingmaterial.

[0181] Also, heat generated by a power conversion circuit 201 iseffectively radiated from the second member 6206 having large thermalconductivity via the substrate 209. This can improve the conversionefficiency and reliability of the power converter 6107.

[0182] Furthermore, electromagnetic waves generated by the powerconverter 6107 can be shut off by the second member 6206 comprising athermally conductive material. This effectively reduces influence onsurrounding electric and electronic apparatuses.

[0183] The characteristic features and effects of the structures of thepower converter, solar cell module (photovoltaic element module), andpower generator explained in each embodiment will be summarized below.

[0184] That is, to realize downsizing of the solar cell module of eachembodiment, the thickness is reduced by fixing the power converter tothe solar cell module main body containing the solar cell. In addition,a material having small thermal conductivity is used as the protectivecase for protecting the power conversion circuit fixed to the solar cellmodule main body. This prevents easy conduction of heat from the solarcell module main body heated to a high temperature to the powerconversion circuit. Furthermore, to allow easy radiation of heatgenerated by the power conversion circuit, a material having largethermal conductivity is used as the member of the protective case forfixing the power conversion circuit. As a consequence, the followingeffects are achieved.

[0185] (1) An intense heat generated by sunlight and conducted to thepower conversion circuit contained in the protective case of the powerconverter via the rear-surface reinforcing material of the solar cellmodule main body is effectively shut off by the low-thermal-conductivitymember of the protective case in contact with the rear-surfacereinforcing material. Heat generated by the power converter iseffectively radiated by the high-thermal-conductivity member in contactwith the power converter. Consequently, a temperature rise of the powerconversion circuit reduces, and this improves the conversion efficiencyand reliability of the power converter.

[0186] (2) To connect the power converter to the solar cell module mainbody, no gap need be formed to prevent easy conduction of heat betweenthe rear-surface reinforcing material of the solar cell module main bodyand the power converter, unlike in the conventional systems. Thisimproves the mechanical strength of the whole solar cell module anddownsizes the solar cell module.

[0187] As has been described above, the present invention can provide asolar cell module (photovoltaic element module) in which a solar cellmodule (photovoltaic element module) main body containing a solar cell(photovoltaic element) is integrated with a power converter forconverting output electric power from the solar cell, and which issuited to downsizing and capable of improving the efficiency andreliability of the power converter.

[0188] As many apparently widely different embodiments of the presentinvention can be made without departing from the spirit and scopethereof, it is to be understood that the invention is not limited to thespecific embodiments thereof except as defined in the appended claims.

What is claimed is:
 1. A power converter comprising a power conversioncircuit for converting an output from a photovoltaic element andoutputting the converted output, and a protective case containing saidpower conversion circuit, wherein said protective case comprises: afirst portion for fixing said protective case to a predetermined portionof a photovoltaic element module having said photovoltaic element; and asecond portion for fixing said power conversion circuit, and said firstand second portions are made of materials different in thermalconductivity.
 2. The converter according to claim 1, wherein the thermalconductivity of the material of said first portion is smaller than thatof the material of said second portion.
 3. The converter according toclaim 1, wherein the material of said first portion is a plasticmaterial containing one member selected from the group consisting ofpolycarbonate, polyamide, polyacetal, modified PPO (PPE), polyester,polyallylate, unsaturated polyester, a phenolic resin, an epoxy resin,polybutyleneterephthalate, nylon, polypropyrene, polyvinyl chloride, andan ABS resin.
 4. The converter according to claim 1, wherein thematerial of said second portion contains one member selected from thegroup consisting of an aluminum plate, stainless steel plate,zinc-plated steel plate, galvalume steel plate, titanium steel plate,and stainless steel plate.
 5. The converter according to claim 1,wherein the material of said second portion is a resin mixed with athermally conductive material.
 6. The converter according to claim 5,wherein the thermally conductive material contains at least one of ametal powder, metal oxide, metal fibers, metal-coated glass beads, andsynthetic fibers.
 7. The converter according to claim 5, wherein thethermally conductive material contains at least one of Al, Cu, Ni, ZnO,SnO₂, Ag, and stainless steel.
 8. The converter according to claim 5,wherein the thermally conductive material contains at least one ofcarbon black, carbon fibers, and graphite.
 9. The converter according toclaim 5, wherein the material of said first portion is a plasticmaterial containing one member selected from the group consisting ofpolycarbonate, polyamide, polyacetal, modified PPO (PPE), polyester,polyallylate, unsaturated polyester, a phenolic resin, an epoxy resin,polybutyleneterephthalate, nylon, polypropyrene, polyvinyl chloride, andan ABS resin.
 10. The converter according to claim 1, wherein said powerconversion circuit is fixed in contact with a surface of said secondportion.
 11. The converter according to claim 1, wherein said powerconversion circuit is fixed away from said second portion.
 12. Theconverter according to claim 1, wherein said power conversion circuit isfixed to said second portion by using fixing means.
 13. The converteraccording to claim 12, wherein said fixing means is mechanical fixationusing a screw or fixation using an adhesive or filler.
 14. The converteraccording to claim 1, wherein an adhesive or filler is packed betweensaid protective case and said power conversion circuit.
 15. Theconverter according to claim 1, wherein said power converter is aninverter which converts DC power into AC power.
 16. The converteraccording to claim 1, wherein said power conversion circuit is mountedon a substrate having a metal core.
 17. The converter according to claim1, wherein said power converter is a DC/DC converter which converts DCpower into another DC power having a different voltage.
 18. Theconverter according to claim 1, wherein said photovoltaic elementcontains one member selected from the group consisting of a siliconsemiconductor, compound semiconductor, single-crystal silicon,polysilicon, amorphous silicon, and thin-film polysilicon.
 19. Theconverter according to claim 1, wherein said photovoltaic element isfilled with a transparent insulating member and contained in a main bodyof said photovoltaic element module.
 20. The converter according toclaim 1, wherein said insulating member is transparent to one memberselected from the group consisting of an ethylene-vinyl acetatecopolymer (EVA), ethylene-methyl acrylate copolymer (EMA),ethylene-ethyl acrylate copolymer (EEA), and polyvinyl butyral resin.21. A photovoltaic element module comprising: a power convertercomprising a power conversion circuit for converting an output from aphotovoltaic element and outputting the converted output, and aprotective case containing said power conversion circuit; and aphotovoltaic element module main body having said photovoltaic element,wherein said protective case comprises: a first portion for fixing saidprotective case to a predetermined portion of said photovoltaic elementmodule having said photovoltaic element; and a second portion for fixingsaid power conversion circuit, and said first and second portions aremade of materials different in thermal conductivity.
 22. A powergenerator using a photovoltaic element module comprising: a powerconverter comprising a power conversion circuit for converting an outputfrom a photovoltaic element and outputting the converted output, and aprotective case containing said power conversion circuit; and aphotovoltaic element module main body having said photovoltaic element,wherein said protective case comprises: a first portion for fixing saidprotective case to a predetermined portion of said photovoltaic elementmodule having said photovoltaic element; and a second portion for fixingsaid power conversion circuit, and said first and second portions aremade of materials different in thermal conductivity.
 23. The generatoraccording to claim 22, wherein said power generator comprises aplurality of photovoltaic element module main bodies, and said pluralityof photovoltaic element module main bodies are connected to said powerconverter.